Field of the Invention
The present invention relates to a bicycle seat cushion lifting and adjusting device and, more particularly, to the bicycle seat cushion lifting and adjusting device capable of overcoming the difficulty of adjusting the height of a seat cushion of a conventional bicycle when the environment is changed from low temperature to room temperature, with the volume of oil inside of the bicycle lifting and adjusting device increased, to maintain the stability of the application.
Description of the Related Art
With reference to FIGS. 1 and 2 for a conventional bicycle seat tube height adjusting mechanism 1, the conventional bicycle seat tube height adjusting mechanism 1 comprises a first tube 10, a second tube 11, a lift adjusting unit 12, and a lift controlling unit 13. The second tube 11 has a bottom end passing into the first tube 10 from a top end of the first tube 10, and the lift adjusting unit 12 is passed and installed inside the first and second tubes 10, 11. The lift controlling unit 13 is provided for controlling the lift adjusting unit 12 to move or stop. The lift adjusting unit 12 has an outer tube 120 and an inner tube 121, and the outer tube 120 is shorter than the inner tube 121. The inner tube 121 is fixed in the outer tube 120, and a gap is formed between the outer and inner tubes 120, 121. The outer and inner tubes 120, 121 have a first nozzle 1200, 1210 and a second nozzle 1201, 1211 disposed at upper and lower ends of the outer and inner tubes 120, 121 respectively. The first and second nozzles 1200, 1201 of the outer tube 120 are sealed by a first plug 123 and a second plug 124 respectively. The first nozzle 1210 of the inner tube 121 has an outer wall coupled to an inner wall of the first nozzle 1200 of the outer tube 120. The second nozzle 1211 of the inner tube 121 contains a valve 12A disposed therein and provided for controlling the inner and outer tubes 121, 120 to be communicated or not to be communicated with each other. The lift adjusting unit 12 has a firing pin 125 extended from the second nozzle 1201 of the outer tube 120 into the second nozzle 1211 of the inner tube 121. The firing pin 125 has a spring 1250, and the spring 1250 has a force constantly pressing and pushing the valve 12A to a closed status. The lift adjusting unit 12 further has a floating piston 126 passed and installed on an outer side of the firing pin 125 and disposed inside the outer tube 120. The floating piston 126 is disposed between the second nozzle 1201 of the outer tube 120 and the second nozzle 1211 of the inner tube 121, and the floating piston 126 is provided for separating the interior of the outer tube 120 into a first oil chamber 1202 and an air chamber 1203. A piston rod 127 is extended from the first nozzle 1200 of the outer tube 120 through the first nozzle 1210 of the inner tube 121 into the inner tube 121. A piston 128 is fixed to an end of the piston rod 127 and disposed in the inner tube 121 for separating the interior of the inner tube 121 into a second oil chamber 1212 disposed at an upper end and a third oil chamber 1213 disposed at a lower end. The inner tube 121 has a plurality of through holes 1214 formed on an inner wall of the inner tube 121 and communicated with the gap 122, and the through hole 1214 is disposed near the first nozzle 1210 of the inner tube 121. With the through hole 1214 and the gap 122, the second oil chamber 1212 and the first oil chamber 1202 are communicated with each other. When the valve 12A is opened by pushing the firing pin 125 by the lift controlling unit 13, oil is communicated with the first, third and second oil chambers 1202, 1212, 1213 and the gap 122. Thus, when the seat cushion is moved upward or downward, the second tube 11, the piston rod 127 and the piston 128 coupled to the seat cushion is moved upward or downward synchronously, while driving the oil to flow through the valve 12A in a forward or reverse direction. When the height of the seat cushion position is adjusted properly, the lift controlling unit 13 is released, so that the valve 12A resumes its closed status, to fix the position of the seat cushion after the adjustment has been made.
When the conventional lift adjusting unit 12 is used in a low temperature environment (such as an outdoor snowy environment), the volume of oil in the first, second and third oil chambers 1202, 1212, 1213 will be decreased due to the drop of temperature. When the valve 12A is opened, the air pressure inside the air chamber 1203 pushes the oil inside the first oil chamber 1202 to pass through the valve 12A to fill up the evacuated space caused by the decreased volume of oil inside the third oil chamber 1213. When the bicycle is run in a room temperature environment (such as an indoor environment), the volume of the oil inside the third oil chamber 1213 will be increased due to the temperature rise, so that the pressure of the third oil chamber 1213 is increased, and the oil inside the third oil chamber 1213 will compress the valve 12A excessively. When a user pushes the lift controlling unit 13, it is difficult for the firing pin 125 to push open the valve 12A, and the height of the bicycle seat cushion cannot be adjusted.